Electrically controlled switching device



July 19, 1966 K. POLASEK 3,261,940

ELEGTRICALLY CONTROLLED SWITCHING DEVICE Filed Oct. 29, 1963 INVENTOR. Kn RL Pamsag Hrromvsvs United States Patent 3,261,940 ELECTRICALLY CONTROLLED SWITCHING DEVICE Karl Polasek, Hagersten, Sweden, assignor to Telefonaktiebolaget L M Ericsson, Stockholm, Sweden, a corporation of Sweden Filed Oct. 29, 1963, Ser. No. 319,812 Claims priority, application Sweden, Dec. 7, 1962, 13,197/ 62 2 Claims. (Cl. 200-87) The present invention refers to a relay, and more specifically to a relay comprising a core of soft magnetic material with rectangular hysteresis loop, a magnetically easily influenced contact device connected to the core, and windings arranged on the core for magnetization of the core when the contact device is to operate and for demagnetization of the core when the contact device is to release.

It is heretofore known to arrange two approximately alike longish windings on a soft magnetic core, which windings through co-operation cause operation of a contact device connected mechanically over the core. Release of the contact device is attained by changing the current through one winding so that two approximately alike and mutually oppositely directed magnetornotive forces are obtained. During the operation of the contact device a certain amount of energy is stored in the core. Half of this stored energy is lost in the next operation. The function of the relay is thus based upon an energy balance. A disadvantage with a relay of said kind is the large energy consumption, which is especially noticed in arrangements comprising a large number of such relays, for instance, in magnetic memories.

An object of the present invention is to eliminate this disadvantage. A relay formed according to the invention contemplates that a winding for demagnetization of the core occupies an approximate length 1 of the whole length of the core l -l-l between the connection points of the contact device. The length 1 is obtained from the where indicates the minimum magnetizing flux through the core when the contact device is to operate;

qb indicates the maximum magnetizing flux through the core when the cont-act device is to release;

R is the total reluctance of the core during operating contact of the device;

R is the total reluctance of the core during released contact of the device.

The invention will be further described in connection with the attached drawing, which schematically shows an exemplary embodiment of the invention.

In the sole figure of the drawing, 1 indicates a semicircular core of soft magnetic material, such as ferrite with a rectangular hysteresis loop. On the core 1, windings and 11 are arranged for magnetization of the core 1 when a contact device comprising elements 2, 21 and 22 connected to the ends of the core 1, is to operate. The winding 11 is essentially longer than the winding 10. In the limit zone between the two windings a hole 12 is arranged in the core 1, through which hole a reading winding 13 passes for reading of the state of the core at a given instant of time. The contact device includes a contact of magnetic material arranged in a glass cover 2, the two contact parts 21 and 22 of the contact being mechanically Patented July 19, 1966 ice fastened to the ends of the core 1. The contact is broken in the rest position; it is closed when the windings 10 and 11 together cooperate to generate a magnetic flux which flows through the core 1 and the magnetic contact parts 21 and 22.

When the contact device is to release, the current direction is changed in the winding 10. If, initially, the entire core 1 is magnetized to the remanence point +Br on the hysteresis loop of the core material, the corresponding part associated with winding 10 of the core 1 will, due to the changed current direction in the winding 10, be magnetized to the remanence point Br. Accordingly, in the limit of the core between the windings, that is, in the region about hole 12, the ferrite material will show a very low permeability, namely the onset of permeability, which reaches a value somewhere between 3 and 5. Low permeability implies high reluctance. In other Words, the limit zone between the windings 10 and 11 will appear as an air gap so that the fl'ux through the contact device substantially decreases and the contact is broken. The amount of energy that is lost in the part of the core 1 on which the winding 10 is arranged is directly proportional to the length of the part of the core in question and isas it appears from the drawing-small. In this embodiment, it is thus no longer a question of energy balance, but rather of control power with small energy consumption.

The winding 10 intended for demagnetization of the core occupies an approximate length 1 of the whole length of the core l +l between the connection points of the contact device. The length is obtained from the relation:

mBX- E 1 min. R1 1:1. 2 an... R 1 min. R1

' Where indicates the minimum magnetizing flux through the core when the contact device is to operate;

indicates the maximum magnetizing fiux through the core when the contact device is to release;

R is the total reluctance of the core during operating contact device;

R is the total reluctance of the core during released contact of the device.

Experimental trials have shown that the relation l /l +l is about the same as or larger than l/7.

In the cases when a plurality of relays of a kind mentioned above are used together, it may be necessary to determine the state of a certain relay (operating or released) quickly and often. It is hereby suitable to arrange reading of the state of the core in the limit zone between the windings with the help of the reading winding 13 passing through the hole 12. When the reading winding 13 is sensed a sharply marked pulse is obtained in this winding if the contact device is closed. It is also to be observed that on operation of the contact device, magnetization of the core is effected within a time interval of some tens of microseconds. The operation of the contacts, on the other hand, requires several hundreds of microseconds. Information about the state of the relay can therefore be obtained quickly from the core Without waiting for the operation of the contact device.

I claim:

1. A switching device comprising first and second reedlike contact members of magnetic material disposed in normally spaced adjacent relationship to define a contact gap therebetween, a single elongated core of magnetically soft material having a substantially rectangular hysteresis loop, said core having first and second end portions magnetically connected to said first and second contact members respectively, a first winding disposed about a first length portion of said core, a second winding disposed about a second length portion of said core, said core being provided with an aperture in the region thereof between said first and second length portions, and a sense winding passing through said aperture for determining the state of magnetization of the region of said core adjacent said aperture and consequently the connection state of said contact members.

2. A switching device comprising first and second reedlike contact members of magnetic material disposed in normally spaced adjacent relationship to define a contact gap therebetween, a single elongated core of magnetically soft material having a substantially rectangular hysteresis loop, said core having first and second end portions magnetically connected to said first and second contact members respectively, a first winding disposed about a first length portion of said core, and a second winding disposed about a second length portion of said core, said second length portion being equal to the first length portion times the fraction where qb is the minimum magnetizing flux through said core when the switching device is to be actuated, rp is the maximum magnetizing fiux through said core when the switching device is to be released, R is the total reluctance of said core when the switching device is actuated and R is the total reluctance of said core when the switching device is released, said first winding being adapted to receive current of a first polarity and said second winding being adapted to receive current of said first polarity so that each of the length portions of said core is magnetized to the same state of remanent magnetization to cause the attraction and said contacting of said contact members, and second winding being adapted to receive thereafter a current of opposite polarity for magnetizing said second length portion to an opposite state of remanent magnetization to create a zone of high reluctance in said core between said windings, which zone induces the magnetomotive to release of said contact members.

References Cited by the Examiner UNITED STATES PATENTS 2,995,637 8/1961 Feiner et al 179-27.54 3,037,085 5/1962 Lowry 200-87 3,056,868 10/1962 Jacobson et al 20087 3,059,075 10/1962 Peek 20087 3,146,325 8/1964 Gribble 200-87 3,217,122 11/1965 Bernstein 20087 OTHER REFERENCES Feiner et al.: The FerreedA New Switching Device, in The Bell System Technical Journal, volume XXXIX, January 1960. Number 1, pp. 18 to 20.

BERNARD A. GILHEANY, Primary Examiner.

B. DOBECK, Assistant Examiner. 

1. A SWITCHING DEVICE COMPRISING FIRST AND SECOND REEDLIKE CONTACT MEMBERS OF MAGNETIC MATERIAL DISPOSED IN NORMALLY SPACED ADJACENT RELATIONSHIP TO DEFINE A CONTACT GAP THEREBETWEEN, A SINGLE ELONGATED CORE OF MAGNETICALLY SOFT MATERIAL HAVING A SUBSTANTIALLY RECTANGULAR HYSTERESIS LOOP, SAID CORE HAVING FIRST AND SECOND END PORTIONS MAGNETICALLY CONNECTED TO SAID FIRST AND SECOND CONTACT MEMBERS RESPECTIVELY, A FIRST WINDING DISPOSED ABOUT A FIRST LENGTH PORTION OF SAID CORE, A SECOND WINDING DISPOSED ABOUT A SECOND LENGTH PORTION OF SAID CORE, SAID CORE BEING PROVIDED WITH SAID AN APERTURE IN THE REGION THEREOF BETWEEN SAID FIRST AND SECOND LENGTH PORTIONS, AND A SENSE WINDING PASSING THROUGH SAID APERTURE FOR DETERMINING THE STATE OF MAGNETIZATION OF THE REGION OF SAID CORE ADJACENT AND APERTURE AND CONSEQUENTLY THE CONNECTION STATE OF SAID CONTACT MEMBERS. 